Since an organic semiconductor element using an organic compound as a semiconductor material exhibits easiness in workability as compared with conventional semiconductor elements using inorganic semiconductor materials such as silicon, it has been expected to realize a low-cost device. Moreover, since a semiconductor material of an organic compound is structurally flexible, it has been expected to realize a device such as a flexible display by using the material in combination with a plastic substrate.
As working processes for organic semiconductors, there is known a dry process by vapor deposition and a wet process using an organic solvent, such as coating, printable, or ink jet. Since a conventional organic semiconductor material has a low solubility in organic solvents and thus it is difficult to apply the wet process thereto, the dry process has been widely utilized. On the other hand, the wet process is easy and inexpensive and is a manufacturing process exhibiting a little environmental burden.
An improvement in carrier mobility is required for an organic semiconductor material. As a method of improving the carrier mobility of the organic semiconductor material, an effective method has not yet been established but it is considered to be important to strengthen intermolecular interaction or control arrangement of molecules. Since an acene compound that is a condensed polycyclic compound has an expanded conjugate system owing to its planar structure and has a strong intermolecular interaction owing to π stacking, it is attempted to utilize the compound as an organic semiconductor material (Non-Patent Document 1).
An acene compound is a compound having a skeleton in which benzene rings are linearly condensed. The acene compound has a small theoretical band gap as compared with polyacetylene and the like and thus an excellent function as an organic semiconductor material is expected and the function is expectable as the number of rings increases. Moreover, the compound has a possibility of changing conductivity depending on a substituent.
In an acene compound having no substituent, solubility in an organic solvent decreases as the number of the rings increases. Therefore, it is difficult to apply the wet process to the acene compound. Also, there is very narrow range for selecting solvent and temperature condition.
There is proposed an acene compound having an increased affinity to organic solvents and being applicable to the wet process, by introducing a substituent such as an alkyl group into the acene skeleton (Patent Document 1).
Patent Document 2 discloses a method for manufacturing an anthracene having a perfluoroalkyl group by a coupling reaction using a heavy metal. As the compound, an anthracene having C8F17-groups substituted at 6- and 13-positions is disclosed. Since the manufacturing method of Patent Document 2 uses a coupling reaction of a halo-substituted acene compound with a perfluoroalkyl iodide in the presence of a heavy metal (Cu), synthesis is vexatious and complicated. Moreover, an organic semiconductor material is required to be highly pure. Therefore, in the case of contamination with a heavy metal, much labor is necessary for ultrahigh purification (sublimation purification etc.).
In order to avoid this problem, it is considered to apply direct polyfluoroalkylation to aromatics without using the heavy metal coupling reaction. There are reports of perfluoroalkylation to benzenes but there is hitherto no report of perfluoroalkylation to an acene compound (Patent Document 3 and Non-Patent Document 2).